Combined rope starter and guard for gasoline engines

ABSTRACT

On an engine having a flywheel blower enclosed in a shroud, a driven clutch element is fixed on the adjacent end portion of the crankshaft, spaced from the shroud. A cooperating driving clutch element is slidable and rotatable on the crankshaft between the driven element and the shroud. A rope pulley is concentrically fixed to the driving clutch element and has an apertured coaxial skirt projecting towards the shroud and releasably engageable with a clip thereon. A cup-shaped outward extension on the pulley encloses the driven clutch element.

United States Patent 1191 Braun .1451 July 10, 1973 COMBINED ROPESTARTER AND GUARD FOR GASOLINE ENGINES [75] Inventor: Daniel E, Braun,Brookfield, Wis.

[73] Assignee: Briggs & Stratton Corporation,

Wauwatosa, Wis.

[22] Filed: May 26, 1972 [21] Appl. No.: 257,320

[52] US. Cl. 123/185 A, 123/41.7, 123/179 SE,

123/185 G [51] Int. Cl. F02n 3/02 [58'] Field of Search 123/179 SE, 185A, 123/185 G, 41.7

[56] j References Cited UNITED STATES PATENTS 3,375,813 4/1968 Hamman123/185 A 2,374,685 5/1945 Kissel et al 123/185 G FOREIGN PATENTS ORAPPLICATIONS 602,072 12/1925 France 123/185 G Primary Examiner- A1Lawrence Srnith Assistant Examiner-W. Rutledge, Jr. Attorney-Ira MiltonJones ABSTRACT.

On an engine having a flywheel blower enclosed in a shroud, a drivenclutch element is fixed on the adjacent end portion of the crankshaft,spaced from the shroud.

- A cooperating driving clutch element is slidable and rotatable on thecrankshaft between the driven element and the shroud. A rope pulley isconcentrically fixed to the driving'clutch element and has an aperturedcoaxial skirt projecting towards the shroud and releasably engageablewith a clip thereon. Acup-shap'ed outward extension on' the pulleyencloses the drivenclutch ele-'- ment.

4 Claims, 3 Drawing Figures PAIENIEU JUL 1 01973 I 3. 744.468

SIEEI1U3 FIGJ.

COMBINED ROPE STARTER AND GUARD FOR GASOLINE ENGINES This inventionrelates to single-cylinder gasoline engines such as are used forpowering lawn mowers, air compressors and similar machines; and theinvention is more particularly concerned with a simple and inexpensivepull-rope starter for such an engine that also serves as a normallystationary guard for the rotating parts at the flywheel end of thecrankshaft.

On a small gasoline engine of the type with which this invention isconcerned, one projecting end of the crankshaft is coupled to a load,and a flywheel mounted on its other end has vanes or blades on itsperiphery for blowing cooling air across the engine body. The flywheelis enclosed in a sheet metal shroud that distributes and directs thecooling air across the hot parts of the engine. The shroud has a ratherlarge air intake opening concentric with the flywheel, through which theadjacent end portion of the crankshaft projects outwardly, and in mostcases the driven element of a starter is secured to this projecting endportion of the crankshaft.

In the interests of safety, it is desirable to have all rotating partsof a power machine guarded by normally stationary enclosures. On anengine, therefore, there should be a guard across the air inlet in theshroud and around the adjacent projecting end portion of the crankshaft.

On a small engine which does not have an electric starter, and which isintended for powering such machines as power lawn mowers and rotarytillers, the manual starter may be of the spring wind-up type or of therope-recoil type, but in either case the starting mechanism is usuallyarranged to have stationary parts which serve as a guard for rotatingparts at the flywheel end of the crankshaft.

However, on engines intended for such construction industry equipment aspumps, generators and air compressors, where the engine runs for manyhours and sometimes for days after each start, a very simple pullropestarter is preferred. Heretofore such non-recoil rope starters haveconsisted of a rope pulley anchored to the flywheel end portion of thecrankshaft, which pulley had a rope receiving slot in one of itsflanges. A knotted end portion of a pull rope was simply engaged in theslot and manually coiled around the pulley, and the engine was tumedover by pulling the free end of the rope. A similar pulley has also beenprovided as an auxiliary manual starter on engines equipped with anelectric starter.

This simple starter was undoubtedly the ultimate in simplicity, low costand dependability, but, offsetting these advantages, it presented anexposed, slotted, rotating pulley that could be dangerous in itself, andit afforded no protection against inadvertent engagement of fingers orclothing against other rotating parts at the flywheel end of thecrankshaft, including the blower vanes on the flywheel. i

The present invention has as its general object to provide a simple,non-recoil rope starter for small engines that is only slightly moreexpensive than the one just described, but which has the very importantfeature of normally serving as a non-rotating guard that protects allrotating parts on the flywheel end of the crankshaft.

It is also an object of this invention to provide a simple andinexpensive rope starter of the character de- I scribed that does notinterfere with the flow of cooling air into the air intake opening inthe shroud but nevertheless serves as an effective guard over thatopening as well as over the end portion of the crankshaft that projectsthrough it.

Another object of this invention'is to provide a simple and inexpensiverope pull starter that is automatically moved to and releasably retainedin a position in which it serves as a guard immediately upon starting ofthe engine and in consequence of such-starting, and

which must be deliberately moved out of that position in order topermitit to be used as a starter.

With these observations and objectives in mind, the manner in which theinvention achieves its purpose will be appreciated from the followingdescription and the accompanying drawings, which exemplify theinvention, it being understood thatchanges may be made in the specificapparatus disclosed herein without departing from the essentials of theinvention set forth in the appended claims.

' The accompanying drawings illustrate two complete examples ofembodiments of the invention constructed according to the best modes sofar devised for the practical application of the principles thereof, andin which:

FIG. 1- is a view in side elevation of a small engine I 'trating amodified embodiment of the invention and with the device shown in itsguard position.

Referring now to the accompanying drawings, the numeral 5 designatesgenerally a single-cylinder gasoline engine that has a blower flywheel 6mounted on its crankshaft 7, at one side of its crankcase body 8. Theflywheel has the usual blower vanes 9 on its periphery for generating astream of cooling air, and it is enclosed within a sheet metal shroud 10that partially embraces the engine body and directs the cooling airacross the hot parts of the engine.

Through a concentric cooling air inlet opening 12 in the shroud a frontend portion of the crankshaft projects beyond the flywheel and out ofthe shroud. To this projecting end portion of the crankshaft there isfixed a driven clutch element 14 of the manual starter of thisinvention. A cooperating driving clutch element 15 comprises part of apulley unit 16 that is normally stationary and serves as a guard for therotating parts at the flywheel end of the crankshaft.

The driven clutch element 14 is fixed to the crankshaft 7 in forwardlyspaced relation to the shroud 10. The pulley unit is both rotatable andaxially slidable on the crankshaft, with its driving clutch elementportion 15 normally disposed between the shroud and the driven clutchelement. In its normal position the pulley unit 16 is contiguous to theshroud, as illustrated in FIG. 1, and is releasably held againstrotation and axial motion by clips 17 on the front wall of the shroud.For engine starting the pulley unit is manually moved forwardly awayfrom the shroud, out of engagement with the clips and into a position inwhich its driving. clutch element is engaged with the driven clutchelement. The pulley unit can then be rotated for engine starting, by

means of a pull rope coiled around it. As soon as the engine starts, theclutch elements cooperate to disengage from one another and move thepulley unit back to its normal guard position, engaged with the clips17.

Turning now to a more detailed consideration of the embodiment of theinvention illustrated in FIGS. 1 and 2, the driven clutch element 14comprises a generally tubular member having a male helical spline 19 onits cylindrical surface and having a concentric rearwardly opening wellor counterbore 20 in which the front end portion of the crankshaft isreceived with a close fit. The driven clutch element is secured to thecrankshaft by means of a bolt 21 that extends through the bore in it andinto a concentric threaded forwardly opening well in the crankshaft. Thedriven clutch element can be keyed to the crankshaft or otherwiseconfined against rotation relative thereto. A washer 22 that is largerthan the outside diameter of the driven clutch element is confinedbetween its front end and the head of the bolt 21 to serve as a stop forthe driving clutch element.

The pulley unit 16 is here shown as comprising three main parts, namelythe driving clutch element which serves as a hub by which the unit rideson the crankshaft, a pulley part 23 in which there is a rope groove 24and which has an integral cup-shaped forward extension 25, and a skirtpart 26 that extends concentrically rearwardly from the pulley part. Thepulley part 23 has a rather large bore 27 therethrough that iscontinuous with the interior of the cup-shaped extension 25. Closelyreceived within this bore is the hub-like driving clutch element 15,which has a female helical spline that is cooperable with the malehelical spline 19 on the driven clutch element. The driving clutchelement also has as its rear a concentric flange-like enlargement 28that is partway received in a shallow well or counterbore in the rear ofthe pulley part. Bolts 29 extending through this flange 28 and threadedinto the pulley part secure the driven clutch element to the pulleypart.

The skirt portion 26 of the pulley unit is made of light foraminousmetal, since it must serve as a guard across the air inlet opening 12 inthe shroud but must not interfere with flow of air into that opening.The skirt part is more or less bowl-shaped, with a flat central portion,as at 30, having a concentric hole therein in which is received theflange 28 on the driving clutch element. A washer-like ring 33, securedto the pulley part by the bolts 29, overlies the flat central portion ofthe skirt, around the edge of the hole therein, and the skirt is spotwelded or otherwise secured to that ring. The periphery of the skirtterminates in an axially rearwardly projecting concentric rim 32. Inthis case the rim is shown provided with a bead or edging 33 of rubberlike material that extends all the way around it, to enable the skirt toengage the hook-shaped spring clips 17 with a detent action, and toprevent drumming vibration between the skirt and the shroud.

The male helical spline 19 extends along only about the front half ofthe driven clutch element, and the driving clutch element 15 has anaxial length which is somewhat less than half of that of the drivenclutch element. Hence when the pulley unit is in its normal position, inwhich the skirt 26 is engaged with the clips 17, the unsplined rearportion of the driven clutch element can rotate freely within thedriving clutch element. However, when the engine is to be started, thepulley unit is manually pulled forwardly to disengage it from the clipsand to bring the male and female splines into engagement. The engine canthen be turned over by means of a rope (not shown) having a knotted endengaged in a slot 34 in the front flange of the pulley and coiled aroundthe pulley. When the engine starts, the helical spline connectionbetween the clutch elements causes the pulley unit to be propelledrearwardly. to its normal position.

The cup-shaped extension 25 of the pulley portion of the unit 16projects far enough forward to clear the front end of the crankshaftwhen the unit is in its normal rearmost position. A concentric hole 35in the end wall of that extension admits an Allen wrench or otherscrewdriver to the bolt 21 that secures the driven clutch element to thecrankshaft. Because the pulley unit rides on the driven clutch element,removal of the latter from the crankshaft permits access to the flywheeland to other parts that are mounted on and near the projecting front endportion of the crankshaft.

The embodiment of the invention illustrated in FIG. 3 differs from thatdisclosed in FIGS. 1 and 2 mainly in having its pulley unit 16' formedessentially in one piece, and in having a somewhat different type ofoneway clutch.

In FIG. 3 the driven clutch element 14"is a more or less disc-like partthat is concentrically secured to the front of the crankshaft 7 by meansof a bolt 21 threaded rearwardly into the crankshaft. On its rear facethe driven clutch element has ratchet-like clutch dogs 41 that cooperatewith similar dogs 42 on a hub portion 15' of the pulley unit that servesas the driving clutch element.

In this case the pulley unit 16' rides directly on the front end portionof the crankshaft, between the driven clutch element and the shroud l0,and its hub portion 15' is a snugly inserted hat-shaped sinteredmetalbearing that has the dogs42 formed on the front face of itsenlarged diameter front end. The bearing of the pulley unit must havelow friction and good resistance to wear, inasmuch as the crankshaftrotates inside it, and the sintered metal, imprgenated with oil,provided these qualities.

The pulley unit 16 is formed with a circumferential rope groove 24 nearits front end, defining a front pulley flange in which there is a slotfor the knotted end of a starter rope. From the rope groove rearwardlythe pulley unit is formed as a generally cylindrical skirt 26 in whichthere are numerous axially elongated slots 43 that admit cooling air tothe air inlet 12 in the shroud. As here shown, the flywheel 6 isequipped with the conventional rotating screen 44 across the cooling airinlet, but of course that-screen can be omitted.

In this case the clips 17' that releasably confine the pulley unit inits normal rearmost position comprise resilient fingers that projectforwardly from the front wall of the shroud and have bowed end portions45 that engage over a circumferential beador ridge 46 on the innersurface of the skirt, at its rear edge. The fingers are under outwardflexing bias, and their ridge portions 45 thus tend to engage over theridge on the skirt with a detent action. Note that when the pulley unitis in its normal position, the fingers or clips 17' are covered by theskirt and cannot catch on clothing and the like.

For uncomplicated molding or casting of the unitary main body of thepulley unit 16', the cup-shaped extension 25' on its front end, whichencloses the driven clutch element, is preferably formed in twopartsQone of them an integral tubular forward extension 48 of thepulley, and the other a cover 49 which fits over the front end portionof that extension. The cover 49 is preferably made of plastic, and itsconnection with the extension 48 should be a readily removable one suchas a snap connection, as here shown, or a bayonet connection.

From the-foregoing description taken with the accompanying drawings itwill be apparent that this invention provides a very simple andinexpensive rope starter for single-cylinder gasoline engines that alsoserves as a normally stationary guard for protecting rotating parts atand near the flywheel end of the engine crankshaft.

Those skilled in the art will appreciate that the invention can beembodied'in forms other than as herein disclosed for purposes ofillustration.

The invention is defined by the following claims:

I claim: I

1. In an internal combustion engine having a crankshaft on which thereis a blower flywheel and having a shroud enclosing the flywheel, saidshroud having a cooling air inlet opening through whichan end portion ofthe crankshaft projects outwardly,

means providing both a manual starter for the engine and a normallynonrotating guard covering said opening and enclosing said end portionof the crankshaft, the last mentioned means comprising:

A. a driven clutch element fixed to said end portion of thecrankshaft'in outwardly spaced relation to the shroud;

B. a pulley unit havin l; a hub portion which is freely rotatable onsaid end portion of the crankshaft and axially slidable between thedriven clutch element and the shroud and which comprises a drivingclutch element,

2. a peripheral pulley portion which is fixed to the hub portion andabout which a pull. rope can be wound,

3. a cup-shaped cover portion fixed to and projecting axially outwardlyfrom said pulley portion and enclosing the driven clutch element and itsadjacent end of the crankshaft, and

4. a skirt portion concentric to the crankshaft and projecting axiallytoward the shroud;

C. cooperating one-way clutch means on the driven clutch element and onthe hub portion of the pulley unit, engageable to constrain the drivenclutch element to' rotate in one direction with the pulley unit andcooperable to translate rotation of the driven clutch element in theopposite direction relative to the pulley unit into axial motion of thepulley unit toward the shroud; and

D. 'a clip on the shroud, engageable with said skirt portion to restrainthe pulley unit against rotation and from which the skirt portion isdisengageable upon axial movement of the pulley unit away from theshroud and to a position of engagement of said clutch means.

2. In an internal combustion engine having a crank-' B. a drivingone-way clutch element rotatable and axially slidable on the crankshaftbetween the driven clutch element and the shroud;

C. cooperating one-way clutch means on said clutch elements, by whichthe driving clutch element is forced axially away from the driven clutchelement when the latter relatively rotates in the direction in. which itis declutched from the driving clutch element;

D. pulley means concentrically fixed to the driving clutch element foraxial and rotational motion therewith and around which a'pull rope canbe wound;

E. a concentric cup-shaped enclosure means fixed -on the driving clutchelement, enclosing the driven clutch element and the portion of thecrankshaft outwardly of it;

P. a concentric skirt fixed on the pulley means, projecting axiallytowards the shroud; and

G. cooperating means on the shroud and on the skirt for releasablyconfining the skirt, and thus the driving clutch element and theenclosure means, against rotation with the crankshaft and against axialmotion away from the shroud by which the clutch elements tend to beengaged.

3. The internal combuation engine of claim 2,'further characterized bysaid cooperating means on the shroud and on the skirt comprising:

l. a finger on the shroud projecting outwardly therefrom generallyparallel to said end portion of the crankshaft and substantially in linewith the radially inner surface of the skirt, said finger beingyieldingly biased radially away from the crankshaft; and

2. cooperating interengaging ridge means on the finger and on the skirt,the ridge means on the skirt extending circumferentially'around theinner surface thereof, said ridge means being engageable with a detentaction upon movement of the pulley means axially into proximity to theshroud.

4. The internal combustion engine of claim 2, further characterized bysaid cup-shaped enclosure means comprising:

l. a tubular concentric outward projection on the driving clutchelement; and v 2. a cover detachably secured to said projection forclosing the open outer end thereof.

1. In an internal combustion engine having a crankshaft on which thereis a blower flywheel and having a shroud enclosing the flywheel, Saidshroud having a cooling air inlet opening through which an end portionof the crankshaft projects outwardly, means providing both a manualstarter for the engine and a normally nonrotating guard covering saidopening and enclosing said end portion of the crankshaft, the lastmentioned means comprising: A. a driven clutch element fixed to said endportion of the crankshaft in outwardly spaced relation to the shroud; B.a pulley unit having
 1. a hub portion which is freely rotatable on saidend portion of the crankshaft and axially slidable between the drivenclutch element and the shroud and which comprises a driving clutchelement,
 2. a peripheral pulley portion which is fixed to the hubportion and about which a pull rope can be wound,
 3. a cup-shaped coverportion fixed to and projecting axially outwardly from said pulleyportion and enclosing the driven clutch element and its adjacent end ofthe crankshaft, and
 4. a skirt portion concentric to the crankshaft andprojecting axially toward the shroud; C. cooperating one-way clutchmeans on the driven clutch element and on the hub portion of the pulleyunit, engageable to constrain the driven clutch element to rotate in onedirection with the pulley unit and cooperable to translate rotation ofthe driven clutch element in the opposite direction relative to thepulley unit into axial motion of the pulley unit toward the shroud; andD. a clip on the shroud, engageable with said skirt portion to restrainthe pulley unit against rotation and from which the skirt portion isdisengageable upon axial movement of the pulley unit away from theshroud and to a position of engagement of said clutch means.
 2. aperipheral pulley portion which is fixed to the hub portion and aboutwhich a pull rope can be wound,
 2. cooperating interengaging ridge meanson the finger and on the skirt, the ridge means on the skirt Extendingcircumferentially around the inner surface thereof, said ridge meansbeing engageable with a detent action upon movement of the pulley meansaxially into proximity to the shroud.
 2. a cover detachably secured tosaid projection for closing the open outer end thereof.
 2. In aninternal combustion engine having a crankshaft and a shroud from whichan end portion of the crankshaft projects outwardly through a coolingair inlet in the shroud, said shroud partly enclosing the body of theengine to direct cooling air thereacross from a flywheel blower on thecrankshaft, means providing both a manual starter for the engine and anormally nonrotating guard over the cooling air inlet and said endportion of the crankshaft, the last mentioned means comprising: A. adriven one-way clutch element fixed to said end portion of thecrankshaft in outwardly spaced relation to the shroud; B. a drivingone-way clutch element rotatable and axially slidable on the crankshaftbetween the driven clutch element and the shroud; C. cooperating one-wayclutch means on said clutch elements, by which the driving clutchelement is forced axially away from the driven clutch element when thelatter relatively rotates in the direction in which it is declutchedfrom the driving clutch element; D. pulley means concentrically fixed tothe driving clutch element for axial and rotational motion therewith andaround which a pull rope can be wound; E. a concentric cup-shapedenclosure means fixed on the driving clutch element, enclosing thedriven clutch element and the portion of the crankshaft outwardly of it;F. a concentric skirt fixed on the pulley means, projecting axiallytowards the shroud; and G. cooperating means on the shroud and on theskirt for releasably confining the skirt, and thus the driving clutchelement and the enclosure means, against rotation with the crankshaftand against axial motion away from the shroud by which the clutchelements tend to be engaged.
 3. a cup-shaped cover portion fixed to andprojecting axially outwardly from said pulley portion and enclosing thedriven clutch element and its adjacent end of the crankshaft, and
 3. Theinternal combuation engine of claim 2, further characterized by saidcooperating means on the shroud and on the skirt comprising:
 4. a skirtportion concentric to the crankshaft and projecting axially toward theshroud; C. cooperating one-way clutch means on the driven clutch elementand on the hub portion of the pulley unit, engageable to constrain thedriven clutch element to rotate in one direction with the pulley unitand cooperable to translate rotation of the driven clutch element in theopposite direction relative to the pulley unit into axial motion of thepulley unit toward the shroud; and D. a clip on the shroud, engageablewith said skirt portion to restrain the pulley unit against rotation andfrom which the skirt portion is disengageable upon axial movement of thepulley unit away from the shroud and to a position of engagement of saidclutch means.
 4. The internal combustion engine of claim 2, furthercharacterized by said cup-shaped enclosure means comprising: